Making Scripts Executable With a Hashbang (Shebang)

Concepts

• Deno.env provides the environment variables.
• env runs a program in a modified environment.

Overview

Making Deno scripts executable can be useful if you want to make, for example, small tools.

Note: Hashbangs do not work on Windows.

Example

In this program we give the context permission to access the environment variables and print the Deno installation path.

#!/usr/bin/env -S deno run --allow-env

/**
 *  hashbang.ts
 */

const path = Deno.env.get("DENO_INSTALL");

console.log("Deno Install Path:", path);

Permissions

You may require to give the script execution permissions.

Linux

chmod +x hashbang.ts

Execute

Start the script by calling it like any other command:

./hashbang.ts

Details

• A hashbang has to be placed in the first line.

• -S splits the command into arguments.

• End the file name in .ts for the script to be interpreted as TypeScript.

• Future plans include supporting the command-line option --ext <type>, relieving this naming restriction. See denoland/deno#5088.

Using hashbang in files with no extension

You may wish to not use an extension for your script's filename. In this case, you can supply one by using the --ext flag:

$ cat my_script
#!/usr/bin/env -S deno run --allow-env --ext=js
console.log("Hello!");
$ ./my_script
Hello!